The present invention relates to container inspection machines and more particularly to a method and apparatus of controlling a transfer of a container from a circular star wheel conveyor of a container inspection apparatus onto a conveyor with a transfer apparatus.
The container inspection machine typically includes a conveyor that is configured to transport containers including inspection machine and a star wheel conveyor which accepts containers from the conveyor, inspects the container at various inspection positions and then discharges the container from the star wheel onto the conveyor for further handling and processing. The conveyor typically is linear and includes a screw transport which spaces containers on the conveyor and aligns the container with a pocket defined in the star wheel conveyor. In a typical star wheel conveyor configuration, the star wheel conveyor defines a plurality of intermediate angular positions and is configured to rotate about a central axis by an actuator, for example a servo motor. The star wheel conveyor receives a container from the linear conveyor rotates it at a discreet speed and is configured to make a number of stops, referred to as a dwell, with specific dwells in the inspection positions. The star wheel conveyor rotates until each container is inspected at the plurality of inspection positions until it reaches a position in which it is discharged from the star wheel conveyor by a transfer apparatus. The transfer apparatus is configured to move the container from the pocket of the star wheel conveyor onto the linear conveyor at a speed and attitude that will not damage the container or upset it from a specific orientation.
Because of different size and configuration of containers different star wheel conveyor configurations are utilized. The outside diameter of the star wheel conveyor is fixed and different sized bottles are accommodated by using a different number of pockets defined in the star wheel. The star wheel conveyor is in a fixed position with respect to the linear conveyor which delivers the containers to and removes the containers from the machine. It can be shown that in an 18 pocket star wheel conveyor there is a dwell position which places a container in contact with an outfeed stripper and outfeed wheel. Such continued configured allows the outfeed wheel to drive the bottle past the intersecting star wheel diameter while the star wheel dwells (stops) and before the next star wheel index or movement. However, for larger bottles, a 9 or 6 pocket star wheel conveyor is typically used in the controller of the servo motor drive of the star wheel conveyor does not provide for a dwell that will allow the outfeed stripper and outfeed wheel to discharge a container. In such conditions, the outfeed of the bottle is governed by the star wheel conveyor forcing the container against the outfeed stripper and the outfeed wheel which is running it a tangential speed matching the linear conveyor speed and since the star wheel conveyor tangential speed is much greater the additive velocity imported to the container by the tangential speed of the star wheel conveyor and the rotational speed of the outfeed wheel results in unpredictable container handling and possible damage.
It is known in the art to avoid the handling problem described above by reducing operational speed of one or more of the components of the inspection machine, i.e. the infeed screw, the linear conveyor, the star wheel conveyor speed or the outfeed wheel speed. Such compromised operational speed reduction reduces the efficiency of the inspection machine which typically operates in the range of 200-400 containers per minute. It is also known to provide in various mechanical guides in the outfeed area of the inspection machine in an attempt to stabilize container discharge over such mechanical devices at costs and setup time which further reduces the efficiency of the inspection machine.
The apparatus of the present disclosure must also be of construction which is both durable and long lasting, and it should also require little or no maintenance to be provided by the user throughout its operating lifetime. In order to enhance the market appeal of the apparatus of the present disclosure, it should also be of inexpensive construction to thereby afford it the broadest possible market. Finally, it is also an objective that all of the aforesaid advantages and objectives be achieved without incurring any substantial relative disadvantage.